In general, in the manufacturing processes of a semiconductor device, a fine pattern is formed using photolithography. In addition, several substrates referred to as transfer masks are normally used to form this fine pattern. The transfer masks are typically provided with a fine pattern composed of a metal thin film and the like on a transparent glass substrate. In addition, photolithography is also used to produce this transfer mask.
In order to miniaturize semiconductor device patterns, in addition to miniaturizing the mask pattern formed on the transfer mask, it is also necessary to shorten the wavelength of the exposure light source wavelength used in lithography. The wavelength of exposure light sources used during production of semiconductor devices has recently become shorter with the transition from KrF excimer lasers (wavelength: 248 nm) to ArF excimer lasers (wavelength: 193 nm).
Binary masks having a pattern of a light shielding film composed of a chromium-based material on a transparent substrate have been known as transfer masks for long time. In recent years, binary masks have also appeared for use with ArF excimer lasers that use a material comprising a molybdenum silicide compound (MoSi-based material) (Patent Literature 1: JP-A-2006-78807). In addition, binary masks have also appeared for use with ArF excimer lasers that use a material comprising a tantalum compound (tantalum-based material) for the light shielding film (Patent Literature 2: JP-A-2009-230112). Patent Literature 3 (JP-A-2010-192503) discloses that a light shielding film may undergo hydrogen embrittlement in the case of carrying out acid washing or washing with hydrogen plasma on a photomask composed of a light shielding film using tantalum, niobium, vanadium or at least two metals comprising tantalum, niobium and vanadium. In addition, the formation of a hydrogen blocking film that provides an airtight coating over the upper surface and lateral surfaces of the light shielding film following formation of a pattern on the light shielding film has been disclosed as means for solving this problem.